Guide blade ring

ABSTRACT

A guide blade ring which divided into segments is secured at the gas guide housing of an axial turbine, for example, of an exhaust-gas turbo-supercharger for a reciprocating internal combustion engine, in which the joints between the individual segments form in the cold condition air gaps that extend approximately in the direction of the blade inlet angle; each segment includes a radially inwardly extending flange at which the respective segment is secured by means of two bolts between an inner cover ring and the gas guide housing whereby the inner cover ring assumes the radial centering function of the segments and the sealing function for the inner joint gaps; a centering bushing is arranged in one of the two bolt bores which surrounds the respective bolt with a spacing and connects with each other the flange and the gas guide housing while simultaneously determining also the position of the segments in the circumferential direction; the bolt bore for the respective other bolt of each segment surrounds the same with a gap.

United States Patent 1191 Leicht [5 GUIDE BLADE RING [75] Inventor: Werner Leicht, Stetten/Meersburg,

Germany [73] Assignee: Motoren-und Turbinen-Union Friedrichshafen Gmbl'l, Friedrichshafen, Germany 221 Filed: Apr.27, 1972 121 Appl.No.:248,094

[30] Foreign Application Priority Data July 16, 1974 Primary Examinerl-Ienry F. Raduazo Attorney, Agent, or Firm-Craig & Antonelli 5 7 ABSTRACT A guide blade ring which divided into segments is secured at the gas guide housing of an axial turbine, for example, of an exhaust-gas turbo-supercharger for a reciprocating internal combustion engine, in which the joints between the individual segments form in the cold condition air gaps that extend approximately in the direction of the blade inlet angle; each segment includes a radially inwardly extending flange at which the respective segment is secured by means of two bolts between an inner cover ring and the gas guide housing whereby the inner cover ring assumes the radial centering function of the segments and the sealing function for the inner joint gaps; a centering bushing is arranged in one of the two bolt bores which surrounds the respective bolt with a spacing and connects with each other the flange and the gas guide housing while simultaneously determining also. the position of the segments in the circumferential direction; the bolt bore for the respective other bolt of each segment surrounds the same with a gap.

11 Claims, 3 Drawing Figures GUIDE BLADE RING The present invention relates to a guide blade ring which subdivided into segments is secured at the gas guide housing of an axial turbine, for example, of an exhaust gas turbo-supercharger for a reciprocating piston internal combustion engine, whereby the joints between the individual segments, in which an air gap is present in the cold condition, extend approximately in the direction of the blade inlet angle.

The admission of gases to an axial turbine of an exhaust-gas turbocharger takes place by way of a ring of guide blades whereby the exhaust gases of the internal combustion engine are fed to the axial turbine under a predetermined angle. The guide blades, which are thereby exposed to the hot exhaust gases, are subjected to a high thermal load. Added thereto is the fact that the turbine of an exhaust-gas turbocharger possesses in the fewest of cases a full and constant loading-also called a dynamic chargingbut for the most part is subjected to a varying, pulsating and partial loada socalled surge load-which leads to differing thermal stresses at the guide'blades.

The fastening of the guide blades at the gas guide housing therefore has to be so constructed that no compulsive forces can result especially by reason of the occurring large and differing thermal expansions.

With known prior art constructions, the guide blades are combined, for example, into a closed ring which is threadably connected with the gas guide housing. However, closed rings are very limited in their free expansion possibility so that with differing thermal loads it may lead to stress cracks and compulsive forces are exerted on the housing.

A construction is also known in the prior art in which a guide blade ring is subdivided into segments. However, in this prior art construction, the inner and outer casing parts of the segments are axially extended opposite the flow direction and are inserted into corresponding ring slots for the purpose of sealing the flow space for the propulsion gas against the cooling medium spaces. As a result thereof, the segments are prevented I in their free expansion.

It is now the object of the present invention to so constitute the fastening and configuration of the guide blade segments of a guide blade ring that an unimpeded expansion of the segments is possible also at high alternating thermal loads, as may occur, for example, with exhaust-gas turbo-superchargers.

The underlying problems are solved according to the present invention in that each segment includes a radially inwardly extending flange, at which it is secured by means of two bolts between an inner cover ring and the gas guide housing, whereby the inner cover ring assumes the radial centering of the segments and the sealing of the inner joint gaps, and in that in one of the two bolt bores a centering bushing is arrangedsurrounding the bolt with a spacing, which connects with each other the flange and gas guide housing and determines the position of the segments in the circumferential direction whereas the bolt bore for the respective other bolt surrounds the same with a gap.

According to a further feature of the present invention, the outer joint gaps .are sealed by an outer cover ring which is equipped with an axial abutment surface for the outer casing portion of theguide blade segments and which in the cold condition surrounds the assembled guide blade ring axially to the abutment surface and radially with a gap.

According to a still further feature of the present invention, one relief slot each is arranged in the outer casing portion of each segment at each second blade channel, which extends approximately in the direction of the blade inlet angle.

The advantages realized with the present invention consist in particular in that also with high alternating thermal loads a fastening, free of any problems, of the guide blades for exhaust-gas turbo-superchargers, is created, in that with the aid of the cover rings no gas losses can occur not withstanding the joint gaps necessarily present, and inthat additionally the economic manufacture of the guide blade segments according to a high-quality casting process is made possible.

These and further objects, features and advantages of the present invention will become more apparent from the following description'when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein FIG. 1 is a partial longitudinal cross-sectional view through an axial turbine and guide blade ring in accordance with the present invention,

FIG. 2 is a front elevational view of an individual guide blade segment, and

FIG. 3 is a partial plan view on a relief slot in the outer casing portion of a guide blade segment in accordance with the present invention.

Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts, a guide blade ring 17 subdivided into segments 11 is secured at the gas guide housing 16 of a conventional exhaust-gas turbo-supercharger (not shown) at a radially inwardly extending flange 18 by means of an inner cover ring 12which seals the inner jointgaps against gas losses, and by means of two bolts 15.

The inner cover ring 12 takes over together with two centering seats 19, 20, the radial centering of the segments 11. The determination of the segments 11 in the circumferential direction takes place by one centering sleeve 14 each arranged in a respective bolt bore 21, which connects with each other the flange 18 and the gas .guide housing 16 and which surrounds the bolt 15 with a gap.

In order not to impair the thermal expansion of the flange 18 in the circumferential direction by the centering sleeve 14 as fixed point, the bore 22 for the respective other bolt is constructed as sufficiently large through-bore.

One relief slot 24each is arranged in the outer casing portion 23 of each segment 11 at each second blade channel, which relief slot extends approximately in the direction of the blade inlet angle. A bending stress of the guide blades as a result of the larger thermal expan- .sion of the outer casing portion 23 with respect to the shorter inner casing portion 25 is effectively avoided thereby.

An outer cover ring 13 which seals the outer joint gaps between the segments 11 and the relief slots 24 against gas losses, is provided with an axial abutment surface 26 for the outer casing portion 23 of the segments 11 and surrounds in the cold condition the assembled guide blade ring 17 axially with respect to the abutment surface 26 and radially with a gap, whence also in the radial and axial direction the thermal expansion of the segments 11 can take place unimpairedly without the possibility that any compulsive forces or stresses can occur.

While I have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art and I, therefore, do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

What I claim is:

1. A guide blade ring and support arrangement for attaching said guide blade ring to a gas guide housing; said arrangement comprising:

a guide blade ring formed of a plurality of segments with joints between individual segments forming respective air gaps in the cold condition of said guide blade ring, each of said segments including a radially inwardly extending flange means,

two circumferentially spaced bolts extending through respective bolt bores in each of said flange means for attaching said flange means to said housing,

and an inner cover ring means separate from said housing for radially centering said segments with respect to said housing and for sealing radially inner portions of said gaps between said segments, said inner cover ring means including a radially outwardly facing surface for radially centering said segments with respect to said housing, said bolts being positioned for clamping said inner cover ring means together with said flange means to said housing.

2. An arrangement according to claim 1, characterized in that the joints between individual segments extend approximately in the direction of the blade inlet angle.

3. An arrangement according to claim 2, characterized in that the guide blade ring is part of an exhaust gas turbo-charger for a reciprocating internal combustion engine.

4. An arrangement according to claim 1, wherein a centering bush means is arranged in one of the two bolt bores of each flange means, said centering bush means being in surrounding relationship to and spaced from the one of said bolts in said bore, said centering bush means being in engagement with said housing and said respective flange for maintaining the respective segment in a predetermined circumferential position with respect to said housing, the other of said bolt bores being larger than the bolt therein to form a gap for permitting thermal expansion.

5. An arrangement according to claim 4, wherein said bolts extend through respective openings in said inner cover ring means.

6. An arrangement according to claim 5 wherein said inner cover ring means includes a radially outwardly facing surface in engagement with said housing.

7. An arrangement according to claim 1 further comprising an outer cover ring means for sealing radially outer portions of said gaps between said segments, said outer cover ring means including an axially facing abutment surface which is engageable with outer casing portions of said segments, said outer cover ring means being dimensioned and configured such that it surrounds said segments with an axial and radial spacing in the cold condition of said guide blade ring.

8. An arrangement according to claim 7, characterized in that the joints between individual segments extend approximately in the direction of the blade inlet angle.

9. An arrangement according to claim 7, characterized in that a relief slot extending approximately in the direction of the blade inlet angle is provided in the outer casing portion of each segment at each second blade channel.

10. An arrangement according to claim 5, characterized in that the guide blade ring is part of an exhaust gas turbo-charger for a reciprocating internal combustion engine.

11. An arrangement according to claim 9, wherein each segment includes a plurality of said relief slots. 

1. A guide blade ring and support arrangement for attaching said guide blade ring to a gas guide housing; said arrangement comprising: a guide blade ring formed of a plurality of segments with joints between individual segments forming respective air gaps in the cold condition of said guide blade ring, each of said segments including a radially inwardly extending flange means, two circumferentially spaced bolts extending through respective bolt bores in each of said flange means for attaching said flange means to said housing, and an inner cover ring means separate from said housing for radially centering said segments with respect to said housing and for sealing radially inner portions of said gaps between said segments, said inner cover ring means including a radially outwardly facing surface for radially centering said segments with respect to said housing, said bolts being positioned for clamping said inner cover ring means together with said flange means to said housing.
 2. An arrangement according to claim 1, characterized in that the joints between individual segments extend approximately in the direction of the blade inlet angle.
 3. An arrangement according to claim 2, characterized in that the guide blade ring is part of an exhaust gas turbo-charger for a reciprocating internal combustion engine.
 4. An arrangement according to claim 1, wherein a centering bush means is arranged in one of the two bolt bores of each flange means, said centering bush means being in surrounding relationship to and spaced from the one of said bolts in said bore, said centering bush means being in engagement with said housing and said respective flange for maintaining the respective segment in a predetermined circumferential position with respect to said housing, the other of said bolt bores being larger than the bolt therein to form a gap for permitting thermal expansion.
 5. An arrangement according to claim 4, wherein said bolts extend through respective openings in said inner cover ring means.
 6. An arrangement according to claim 5 wherein said inner cover ring means includes a radially outwardly facing surface in engagement with said housing.
 7. An arrangement according to claim 1 further comprising an outer cover ring means for sealing radially outer portions of said gaps between said segments, said outer cover ring means including an axially facing abutment surface which is engageable with outer casing portions of said segments, said outer cover ring means being dimensioned and configured such that it surrounds said segments with an axial and radial spacing in the cold condition of said guide blade ring.
 8. An arrangement according to claim 7, characterized in that the joints between individual segments extend approximately in the direction of the blade inlet angle.
 9. An arrangement according to claim 7, characterized in that a relief slot extending approximately in the direction of the blade inlet angle is provided in the outer casing portion of each segment at each second blade channel.
 10. An arrangement according to claim 5, characterized in that the guide blade ring is part of an exhaust gas turbo-charger for a reciprocating internal combustion engine.
 11. An arrangement according to claim 9, wherein each segment includes a plurality of said relief slots. 